This invention relates to an improved broaching tool chip remover, and more particularly to a rolling brush cleaning assembly for removing metal chips from a broaching tool without a rubbing or scrubbing action of the brush and without power drive assistance to the brush assembly.
One example of a large machine mounted broaching tool comprises an elongated metal cutting bar of generally rectangular cross-section having a longitudinal row of spaced apart metal cutting tool projections projecting laterally from along a longitudinal edge of the bar. The bar is generally passed perpendicularly to a surface of a workpiece to cut or gouge a groove or slot therein with a peripheral shape comparable to the shape of the cutting tool projections. The size of the cutting tool projections on the bar vary progressively along the bar so that all or a part of the periphery of the slot being cut, is progressively increased in size to a final dimension correlated to the size of the largest cutting tool projections in the row. The cutter bar may also have its cutter tool projections extending upwardly from its horizontal plane, an arrangement similar to a gear rack, the cutter projections being represented by the gear teeth of the rack.
As the cutter bar passes along the workpiece to remove a layer of metal, a chip of the removed metal curls into the space between cutting tool projections. Ordinarily this curled chip will fall from between cutter projections when the cutter bar passes away from the workpiece. However, should these chips not fall from the cutter bar, they may accumulate between cutter projections to an extent which deleteriously interferes with the cutting action of the broach.
Among the more common reasons for failure of the metal curl chips to fall away from the cutter bar are (1) the curled chip becomes frictionally engaged or wedged in the space between spaced cutter projections, and (2) because of the high temperatures involved in metal cutting processes, cutting oils are used in large quantity to provide cooling as well as cutting efficiency. However, it is difficult for this oil to penetrate deep into the workpiece at the precise location of the metal cutting action with the result that the temperatures of the cutting tool projection edge and the curled chips are sufficient to cause a welding reaction which firmly attaches the chip to a cutter projection.
The foregoing description is indicative of a need for metal chip removal and particularly a need for auxiliary and positive means to remove wedged or joined metal curls from the cutter bar. Passing the bar through a steel wire brush in abrading or rubbing contact with the cutter projections to forcibly remove metal curls causes the cutter edges to cut off the wire bristles and rapidly lead to ineffectiveness of the rubbing brush procedure, particularly for smaller or thinner cutter bars which the cutter shortened bristles fail to reach. Power drive wire brushes have been employed to vigorously scrub a broach cutter bar to remove metal chips. Power driven brushes tend to cause undesirable wear on the broaching tool and are not readily adjustable for broaching tools of different thicknesses with the result that larger broaching tools tend to cut the wire bristles from the brush.